Date of Award
Master of Science
Crop Production and Physiology
The control of bacterial plant and seedling diseases is challenging, and when not controlled, cause a decrease in yield and seed quality. Common bactericides used to treat these diseases, such as antibiotics and copper-based compounds, often harm the environment and increase bacterial resistance. Biological bactericides such as beneficial bacteria and bacteriophages are alternatives with less side-effects, and added benefits. Bacteriophages applied to leaves, soil and seeds control bacterial diseases; however, they often require protection against adverse environmental conditions. Seed coating formulations provide such protection while requiring only small amounts of bactericides. To protect Clavibacter michiganense subsp. nebraskense (CN8) bacteriophages against drying and dry storage we incorporated them into polymers before coating them onto maize seeds (Zea mays subsp. Mays). These bacteriophages are active against Clavibacter michiganense subsp. nebraskense (CMN), the causal agent of Goss’s wilt. The polymers had a polyvinyl backbone and alcohol, ether, and pyrrolidone functional groups, and were formulated with stabilizers (e.g., sucrose, skim milk and whey protein isolate). Bacteriophage activity over time was dependent on the polymer functionality and stabilizers used. Some formulations maintained active bacteriophage for at least 7 months at 10ºC and 4 months at 26ºC. Seed coatings had no effect on germination rate or seedling vigor, successfully removed CMN in artificially contaminated maize seeds, and limited seed transmission of the bacterium. Combining specific bacteriophages with seed coating polymers led to storable seed coatings on maize. Similar bacteriophage coatings are possible against other seed-borne and soil-borne pathogenic bacteria providing a new biological bactericide with less environmental impact.
Kimmelshue, Chad, "Bioactive seed coatings against Goss’s wilt using stabilized bacteriophages in polymers" (2018). Graduate Theses and Dissertations. 17230.